The present invention relates to keyboard switches of the double depression type which are commonly found on keyboards whereby depression of the actuator of the keyswitch to a first position causes a representation of the character to be reproduced, while further depression of the actuator to a second position causes the representation to be cyclically repeated as long as the actuator remains depressed.
More particularly, the present invention relates to a switch of the described type in which depression of the actuator to the first position alters the location of a magnetic field, produced by one or more permanent magnets secured to the actuator, relative to a first magnetic core in order to permit inductive coupling between a drive line wire and a first sense line wire that thread the first core so as to provide a first signal, or a "single character" signal; in which depression of the actuator further to the second position alters the location of the magnetic field relative to both the first magnetic core and to a second magnetic core in order to permit inductive coupling between the drive line wire and the first sense line wire and also between the drive line wire and the second sense line wire which thread a second magnetic core so as to provide a second signal, or a "repeat character" signal.
U.S. patent application Ser. No. 525,416 filed Nov. 20, 1974 in the names of Victor Bernin, Robert Madland and C. Knoll and entitled, "Magnetic Keyswitch" is a continuation of U.S. patent application Ser. No. 474,571 filed May 30, 1974 and now abandoned, which in turn was a continuation of U.S. patent application Ser. No. 388,510 filed Aug. 15, 1973 and also now abandoned. These applications show a magnetic switch which utilizes a single saturable magnetic core that is mounted in a unitary insulating support assembly which also supports the drive line and sense line wires.
A unitary support assembly is a highly desirable feature for many applications since the depressible actuator and key stem of the switch can easily be separated from the magnetic core and its associated sense and drive line wires so that components of the switch, such as a return spring, can be replaced without complete dismantling of the switch, in particular, without unsoldering the drive and sense line wires from a printed circuit board to which they are connected. Accordingly, it is an object of the present invention to provide a double depression magnetic keyswitch which employs a unitary support assembly.
The unitary support assembly of the aforementioned U.S. application Ser. No. 525,416 also was constructed with integrally formed cantilever shaped resilient braces which supported the magnetic core in such a manner that the braces were free to yield so as to relieve molding pressures on the core which might otherwise result from shrinkage during molding of the support assembly. It is therefore another object of the present invention to provide a double depression magnetic keyswitch in which molding pressures are relieved from both of the magnetic cores of the switch.
In addition to the foregoing objects, the present invention has a further object of providing the desired double depression switch in a manner such that it utilizes a minimum of parts and such that the support assembly for the switch may be retained in the same housing as the switch of the aforementioned Bernin et al patent applications.